I did take a look at the upgrade procedure fo unlocked bootloader here:
My FP4 fairphone4 says “Your device has loaded a different operating system” on boot, as I have an unlocked bootloader (I remember not locking it).
I updated directly from 6.14 → 7.5 as described in:
I still did run into the “Reason: init_user0_failed” after updating to 7.5.
I tried to switch the “active slot: a” to “b”.
Entered fastboot, run `fastboot devices` on my laptop, which did not show a device
Then after a few reboots it switched to “active slot: b” but still failed, and with the following boot it worked fine and booted back to 6.14
Any advice? Does this mean that my bootloader is locked? In fastboot I saw “secure boot: yes”..